The AHL gives us an interesting testbed for goaltending statistics - while the NHL gives very few reps to goaltenders who are below replacement level, the AHL is primary below-replacement goalies, along with NHL-caliber goalies who have yet to be promoted. Here are the totals over the last six seasons:
|AHL No NHL||823||2569||680|
|< 300 Shots||827||2551||676|
|> 300 Shots||830||2764||700|
The first line is the save percentage for all shootout shots taken in the NHL; line 2 is for the AHL. Line 3 is the AHL save percentage by goaltenders who did not play in the NHL; Line 4 is for players who faced 1-300 shots in the NHL; and Line 5 is essentially goaltenders who became regulars in the NHL. It's very likely that there's a true talent difference between those two groups.
Incidentally, if we look at goaltenders who faced between 25% and 75% of their total shootout shots in the NHL, they posted a 718 save percentage in the AHL and a 677 save percentage in the NHL. This is obviously in a much smaller sample size, but I wouldn't be surprised if there was also a not-insignificant difference in shooter skill in the NHL vs the AHL!